Screening for Chlamydia trachomatis at the time of routine Pap smear in general practice: a cluster randomised controlled trial

OBJECTIVE: To determine whether asking general practitioners to offer chlamydia screening at the same time as Pap screening increases chlamydia screening rates. DESIGN: A pragmatic cluster randomised controlled trial. PARTICIPANTS AND SETTING: Doctors from 31 general practices in the Australian Capital Territory performing more than 15 Pap smear screens per year, and all women aged 16-39 years attending those practitioners between 1 November 2004 and 31 October 2005. INTERVENTION: Doctors in the intervention practices were asked to routinely offer combined chlamydia and Pap screening to eligible women; doctors in the control practices were asked to implement screening guidelines based on a risk assessment of the individual patient (ie, usual practice). MAIN OUTCOME MEASURE: Chlamydia screening rate per visit. RESULTS: There were 26 876 visits by eligible women during the study period: 16 082 to intervention practices and 10 794 to control practices. Chlamydia screening occurred during 6.9% (95% CI, 6.5%-7.3%) of visits to intervention practices and 4.5% (95% CI, 4.1%-4.9%) of visits to control practices. After controlling for clustering and potential confounders, there were twofold greater odds of chlamydia screening occurring during a visit by an eligible woman to an intervention practice than to a control practice (adjusted odds ratio, 2.1 95% CI, 1.3-3.4]). CONCLUSION: Combining chlamydia and Pap screening increases the rate of chlamydia screening in general practice. Implementing this approach would require little additional infrastructure support in settings where a cervical screening program already exists.